Recognizing Delayed Neurotoxicity and Immune Effector Cell Enterocolitis

Surbhi Sidana, MD, asks about 2 less common but important delayed toxicities: delayed neurotoxicity and immune effector cell enterocolitis. Doris Hansen, MD, describes delayed neurotoxicity, including parkinsonism, as occurring in fewer than 1% of patients in earlier disease lines, typically beginning 2 to 3 weeks after infusion and monitored for several months, with signs such as flattened affect, a shuffling gait, or subtle depression that require high clinical vigilance to detect. Dr. Hansen describes immune effector cell enterocolitis as a less recognized, generally grade 3, non-bloody diarrhea that onsets on average around 3 months after infusion, more commonly involving the duodenum, and notes that evaluation should include both upper and lower endoscopy since gross findings can look benign while pathology shows graft-versus-host disease-like changes, sometimes with further testing such as immunohistochemical staining or T-cell receptor sequencing to confirm clonality. Dr. Hansen emphasizes that close collaboration with infectious disease and gastroenterology colleagues, along with community provider education on recognizing these symptoms and their timing, is central to diagnosis and treatment.